People who take Truvada, the once-a-day pill that prevents HIV, are no more at risk for dangerous side effects than those who take an aspirin a day to prevent heart attacks, according to a new study.

Researchers compared Truvada and aspirin by looking at the drugs’ risk profiles in large, published studies. Although the two drugs come with distinct side effects — Truvada most commonly causes dizziness, vomiting, and weight loss, whereas aspirin is most commonly associated with bleeding problems — the frequency of side effects is roughly equivalent.

But the drugs have very different reputations, among both doctors and the general public. Century-old aspirin, when taken as a preventative tool against heart attacks, is viewed as an everyday medication, no big deal. But Truvada, also known as pre-exposure prophylaxis (or PrEP), is a new pill, intertwined with the loaded issues of HIV and sex habits, and mired in uncertainty.

“Everyone’s got aspirin in their medicine cabinet,” Jeffrey Klausner, professor of medicine and public health at the University of California, Los Angeles, and lead author of the study, told BuzzFeed News. “But as a physician I’ve seen people come into the hospital and die from aspirin overdoses — people can be allergic.”

The side effects of each drug are markedly different, Klausner noted, and affect different organs. But after crunching the numbers, he said, “it really looked like I could say Truvada compared favorably, in terms of its safety profile, to aspirin.”

An estimated 52% of American adults aged 45 to 75 are prescribed a daily aspirin to prevent cardiovascular and gastrointestinal diseases, including heart attacks and cancer.

Truvada, which was approved by the FDA in 2012, has been shown to have roughly 92% efficacy in preventing transmission of HIV. The CDC estimates that about 1.2 million Americans are at high enough risk for contracting HIV that they should be prescribed the drug. But only about 21,000 currently get it.

According to Klausner, who trains doctors around the country on how to treat and prevent HIV, much of this has to do with ambivalence about prescribing otherwise healthy individuals a daily pill.

“A lot of the concerns I hear from providers are about safety,” Klausner said. “There have been continued voices saying, ‘Wouldn’t it just be better if people used condoms, or reduced their number of partners?’ Those are important strategies, but they don’t work for everyone.”

The issue of doctor awareness about PrEP is one of the biggest barriers to its wider use.

The new study “is an interesting thought experiment,” Dawn Smith of the CDC’s Division of HIV/AIDS Prevention, told BuzzFeed News. But, she added, “I’m not sure it addresses the safety concerns that some clinicians have.”

Smith noted a CDC study showing that in 2015, about one-third of primary care doctors and nurses had never heard of Truvada. Beyond the lack of awareness, she said, doctors don’t want to cause any side effects, no matter how minor, in otherwise healthy patients.

In his analysis, Klausner looked at the “NNH” — or “number needed to harm” — meaning the number of people who take the drug before one person experiences a harmful side effect. The NNH for Truvada in gay men or transgender women was 114 for nausea and 96 for unintentional weight loss. In women, side effects appeared more frequently, with 1 in 56 women experiencing nausea, 1 in 41 vomiting, and 1 in 36 mildly elevated liver enzymes.

Rarer adverse events for Truvada include kidney problems and a small decrease in bone mineral density, but Klausner notes that both of those effects have been shown to be reversible once the medication is discontinued.

In contrast, aspirin had an NNH of 15 for bleeding problems and 20 for easy bruising. Rarer problems included ulcers and other gastrointestinal problems.

Because it’s so much older, aspirin has been tested in many more people with many more years of follow-up, Klausner noted. Because Truvada is a relatively new drug, it will take awhile to accrue the data needed to make its long-term safety bulletproof.

In the meantime, however, Klausner hopes more doctors will educate themselves about the HIV prevention drug. And after that, he said, “we should work to make it the same price as aspirin.”